Note: I've only seen this on OSX – I tried it on Vivaldi in Windows and Linux, but it didn't happen there, so I don't know if it's a OSX version of Vivaldi thing, or if somehow just my own OSX Vivaldi copy is messed up somehow. Could anyone else quickly try going over to https://news.google.com, try to click on one of the "More [somecategory] stories" section-expanding links, and report back if it works?

I can replicate the issue with the slightly older build that I am primarily using (the one before the bug was introduced that currently prevents Mac snapshots to be released), but the issue you describe is no longer present in the most recent internal build. So no further bug report is required.

When reporting issues, please always include which Vivaldi version and which version of your operating system you are using.